This is a command-line option for the
mysqld commands (arg: Required).
If non-zero, number of threads to spawn to apply in parallel events on the slave that were group-committed on the master or were logged with GTID in different replication domains. Note that these threads are in addition to the IO and SQL threads, which are always created by a replication slave
See also: mariadbd & mysqld for MariaDB Enterprise Server 23.08, in 23.07 ES, in 10.6 ES, in 10.5 ES, in 10.4 ES, in 10.3 ES, in 10.2 ES, in 10.6 CS, in 10.5 CS, in 10.4 CS, in 10.3 CS, and in 10.2 CS